This application claims priority of European Patent Application No. 00810993.6 filed Oct. 26, 2000.
The present invention relates to a bracelet clasp comprising two branches articulated to one another by a respective first one of their ends in order to make it possible to fold a first one of these branches over and/or into the second of said branches, and to unfold it in order to place it substantially in the extension of this second branch, while their respective second ends are intended to be connected to two ends of a bracelet, particularly a bracelet for a wrist watch, these two branches including mutual attaching means for holding them in the folded position.
This type of clasp is well known and exists in the form of a number of variants. In certain clasps, one end of the bracelet is connected to the branch of the clasp which is folded over or into the other branch by a cover the parallel lateral faces of which, which are on either side of the clasp in the closed position, include several pairs of transversely aligned and longitudinally spaced holes which are intended to receive the articulation pin at the end of the bracelet. These pairs of holes make it possible to adjust the length of the bracelet. In other clasps of this type, the end of the bracelet is articulated directly to the second end of this first branch so that, in the closed position, the bracelet hides the clasp.
In some bracelets of this type, the branches which are articulated to one another are made from stamped sheet metal and cover one another in the folded position. These branches are curved in order to match the shape of the wrist. The attachment of these branches to one another is a function of the radius of curvature of the curve. Given that these blades are made from sheet metal, it is possible to modify the radius of curvature of the curve in one direction or in the other in order to adjust the force of attachment between these blades.
A bracelet of this type has already been proposed, particularly in EP 0865742, in which the branches of the clasp are machined in a thicker and therefore more rigid material which allows no further adjustment of the attaching force by modifying the curves of these branches. With such a clasp, as the attaching force of the branches is no longer adjustable by the abovementioned simple means, it is therefore necessary to design precise and durable attaching means. This is why this clasp includes attaching elements which are added to the cover of the clasp and positioned inside it, firstly by means of their shape, which matches a portion of the inside of the cover, and, secondly, by a rod traversing these attaching elements and fixed to their two ends in the lateral faces of the clasp cover which are arranged on either side of the clasp.
This arrangement presents various drawbacks, one of which arises from the fact that this clasp has to be a clasp with a cover, since it is this which serves to receive the attaching elements. A further drawback arises from the fact that all the force required to separate the attaching elements is supplied directly by the user, so it is impossible to exceed a certain limit, to the detriment of the security of the closure. A further drawback arises from the fact that, as in the majority of clasps of this type, opening is obtained directly by pulling on the cover, as this offers a large gripping surface, which increases the risk of unexpected opening of the clasp.
The object of the present invention is to improve the closure security of this type of clasp against unexpected opening both on account of a catching and on account of a pulling force in the wake of a blow to the wrist or of violent impacts such as those which may arise when the user applauds or when he strikes his fist on a table, for example. The object of this invention is also to facilitate opening of the bracelet while still making it possible simultaneously to increase the force necessary for separating the attaching elements. A further object of this invention is to allow the branches of the clasp and the bracelet connected to these branches to pivot through at least 180xc2x0 in order to obtain maximum opening of the clasp and thus to facilitate the passage of the hand through the bracelet. A yet further object of the invention is to make it possible to have a clasp with a base which is substantially identical when the clasp includes a cover and when it does not include one.
To this end, the subject of the present invention is a bracelet clasp of the abovementioned type.
One of the advantages of the proposed solution, in addition to those ensuing from the abovementioned objects, lies in its simplicity and the small number of parts required. Indeed, despite the various improvements of the clasp according to the invention, it may be observed that these are not obtained to the detriment of the simplicity and thus of the reliability of the solution proposed. For the user, handling of such a clasp is characterized by a high level of convenience, giving him a sensation of great security, which is enhanced by the appearance of the clasp, which constitutes a veritable small precision mechanism.